The term power system comprises power generation as well as power transmission and distribution systems and their power related components, such as power generators, power transformers, breakers, transmission and distribution lines etc.
Nowadays, the operation of a power system is continuously monitored in order to collect data about the operational state of the system and to be able to react quickly on deviations from the normal operation state and especially on faults. The collected data may additionally be stored to use them at a later time for evaluation purposes. The monitoring is usually based on measurements of electric quantities of the power system. As a result, to monitor means nowadays to detect events only after they have occurred.
In recent developments, monitoring was supplemented by the aspect of predicting a fault in a power system in order to overcome the problem that conventional monitoring only allows a reaction on a fault after the fault has happened and possible damage was done. In U.S. Pat. No. 6,917,888 B2, a method to detect faults in a power line network is described where faults are anticipated based on frequency data. In US 2007/0052426 A1, a failure prediction method for a power transformer is described which uses a frequency domain transfer function of the transformer to estimate the health of the transformer. The frequency domain transfer function can be computed using a Fast Fourier Transform (FFT) of measured input and output wave forms of the transformer.
In both documents solely the aspect of failure prediction is addressed and in both methods, the failure prediction is carried out in the frequency domain.
It is an object of the present invention to provide a method and a device of the kind described above which allows the prediction of a state of a power system to be used for more than just failure prediction purposes.